On page 5 the OP rephrases the question into whether Sith philosophy is evil, so that was pretty much what I based my answer on.
However, if we follow your line of thought by including Sith culture into our judgement, then we must be clear that culture and philosophy are two distinct concepts.
Sith culture is 'bad' in terms of western standards of ethics as so many have pointed out.
Even by the classical standards of utilitarianism where the goals justify the means, sith culture of behavior is ethically bad. Actions that would increase the overall satisfaction of the Empire would be deemed morally good, however SIth culture seems to also encourage individuals to satisfy their own interests at the expense of its community by imposing harm onto fellow citizens (thus bad).
I also agree with your post regarding Sith culture being a defunct-version of social-Darwinism. It seems as the contradictions within Sith culture tends to push Sith society into a Hobbesian state of nature, where all individuals war against each other. As we see in-game, the Empire has legal rules of conduct, but in practice there is constant scheming with the likely potential of death to the one who looses. An argument could be made that the constant-scheming is restricted to the "elite" of the society (force users and higher military command) and not to the masses in general. Yet who would actually want to live in such a society where tomorrow could very well be your last? Whether one is a force-user or not, the average person X with some degree of rationality combined with a will to survive is not going to passively overlook that the **** is going to hit the fan.
Though, one could wonder whether being a force-user (or perhaps just being dark-sided) distorts rationality.
When Anakin went darkside he seemed to become quite the nutbag.